How to add custom calculations in your payment form?

"they can specify the quantity and the form tells them the total cost"- Google Docs Editors Community

When the amount depends on an answer, such as how many tickets someone wants, people need to see the total before they pay. Google Forms has no formulas. You can work the amount out in Google Sheets, but only after the form is in, and then you write to each person with what they owe. With Neartail, you write the formula once in your Google Form. Each person sees the amount change as they fill it in and pays that amount when they submit.

Let's start. Create your form and follow the steps below.

Set up payments

  • On the page that opens, click Enter your form name, type a name and click Generate.
  • Check the outline it suggests and click Proceed. Your form opens on the Edit tab.
The tabs Edit, Preview, Share and Orders, with Edit marked
  • When it asks "Do you want to collect payment on form submit?", click Yes.
The Payment form dialog asking if you want to collect payment on form submit, with Yes marked
  • If PayPal isn't under Manual payments, your form is in a currency PayPal doesn't take. Close the Payments panel, click the gear icon in the After payment row, the last row above the Submit button, select the currency you charge in and click Save. Then click Edit in the Payments row.
The Button tab of the panel, with USD selected in Currency, and Currency and Save marked
  • Under Manual payments, turn on PayPal, enter your paypal.me username and click Save.
The Payments panel with PayPal turned on under Manual payments, the paypal.me username filled in and Save marked

Write the formula

Order Amount is the amount people pay. Here it becomes the number of tickets times the ticket price.
  • Delete the product cards you don't need with the delete icon at the bottom of each card.
  • Click Add field in the toolbar on the right and enter the question your formula reads, such as Number of tickets.
A question card titled Number of tickets, beside the toolbar with Add field marked
  • Click the Order Amount field, click the Advanced setting icon and click Answer. In Calculate, type @ and pick Number of tickets from the list, then type the rest, such as * 100. Click Save.
The Answer tab of the Order Amount field, with the formula Number of tickets * 100 in Calculate, and Answer, Calculate and Save marked
  • Click Preview and fill in the form to try it.
The tabs Edit, Preview, Share and Orders, with Preview marked
When someone enters the Number of tickets, Order Amount shows the amount before they submit, and that is what they pay. To check each payment, read How to see who has paid in Google Forms?

Summary

When the amount depends on an answer, Google Forms has no formula to work it out, so you calculate it afterwards and write to each person. With Neartail, you write a formula in the Order Amount field and people pay that amount when they submit the form. Create your form and complete the steps above. If you have any questions, write to support.

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